Feature request: output progress indicator in --print mode

Summary

When running claude --print (non-interactive mode), there is no visual feedback while the model is working. For long-running tasks with multiple tool calls, the terminal appears frozen until output is finally printed.

Proposed behavior

Output a small progress indicator (e.g. a period .) to stderr for each tool call made during execution. This gives users a sense that work is happening without polluting the actual stdout output.

Example:
\\\
$ claude --print "refactor this file"
...........
<final output here>
\\\

Why this matters

• --print mode is commonly used in scripts and pipelines where the process may run for tens of seconds or minutes
• Without feedback, it's impossible to distinguish "still working" from "hung"
• Writing progress to stderr keeps stdout clean for piping

Alternatives considered

• A --progress flag to opt in to this behavior
• A spinner instead of periods
• A --quiet flag to suppress it if added by default